A number of methods are known for increasing, by physical, chemical or combined processes the B-10 content of common boron compounds. These methods include distillation, solvent extraction, and ion exchange of the boron compounds.
One method for boron isotope separation is ion exchange of aqueous solutions of boric acid as discussed in "Separation of Boron Isotope by Means of Weak-Base Anion Exchange Resin", Kotaka et al., Research Laboratory of Nuclear Reactor, 1973, Tokyo Institute of Technology. In this study, aqueous solutions of boric acid were passed through ion exchange columns depositing borate ions on the resin. The resin was then eluted with pure water and the B-10 content of the effluent fractions were found to be enriched in the B-10 isotope at the end of the elution. It has also been shown that separation of the B-10 and the B-11 borate isotopes can be accomplished through ion exchange using hydrochloric acid to displace the boric acid molecules from the resin material. The employment of an ion exchange resin to separate isotopes of an element using a chemical reaction to effectuate the isotopic separation is discussed in Isotope Separation, Villani, S., American Nuclear Society at p. 61-63.
Natural boric acid solutions, containing a B-10 to B-11 atomic isotope ratio of 19.8:80.2, are used as control fluids in nuclear power plants. It is known that the B-10 isotope is responsible for nuclear reaction control due to its neutron capturing ability. B-10 enriched boric acid solutions, which contain a B-10 to B-11 atomic isotope ratio in excess of 19.8:80.2, are not currently employed in reactor coolant systems since the B-10 enriched solutions may cost as much as $3.00 (U.S.) per gram of B-10 while the reactor grade natural boric acid solution may only cost $1.00 (U.S.) per pound of boron. Therefore, it would be most advantageous to be able to enrich boron containing products in their B-10 content using an inexpensive process.